#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <linux/if_tun.h>
#include "port.h"

static void send_tap(int fd, void *packet, int len, void *unused) {
	int n;

	n = write(fd, packet, len);
	if (n != len) {
		if (errno != EAGAIN)
			perror("send_tap");
	}
}

int open_tap(char *dev) {
	struct ifreq ifr;
	int fd, err;

	if ((fd = open("/dev/net/tun", O_RDWR)) < 0) {
		perror("Failed to open /dev/net/tun");
		return (-1);
	}
	memset(&ifr, 0, sizeof(ifr));
	ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
	strncpy(ifr.ifr_name, dev, sizeof(ifr.ifr_name) - 1);
	if (ioctl(fd, TUNSETIFF, (void *) &ifr) < 0) {
		perror("TUNSETIFF failed");
		close(fd);
		return (-1);
	}
	err = setup_port(fd, send_tap, NULL, 0);
	if (err)
		return (err);
	return (fd);
}

